1. Field of the Invention
The present invention relates to an image forming apparatus and, particularly, to an image forming apparatus that stops driving of a color developing device during black and white mode and drives the color developing device during color mode.
2. Description of the Related Art
Some electrophotographic color image forming apparatus prevent deterioration of a color developing device caused by driving the color developing device when not involved in image formation and deterioration of toner caused by unnecessary agitating of the toner by coupling a color developing device to a drive motor to drive the color developing device only during color mode and separating the color developing device from the drive motor to stop the color developing device during black and white mode. Conventionally, whether a developing device is in a coupled state or a separated state is detected by a position sensor (separation sensor) that detects a position of a driving force transmission mechanism such as a cam which couples/separates the drive motor and the developing device with/from each other.
However, providing the position sensor requires installation space for the position sensor and also increases cost.